Rechargeable batteries manufactured from laminates of solid polymer electrolytes and sheet-like electrodes display many advantages over conventional liquid electrolyte batteries. These advantages include: lower overall battery weight; higher power density; higher specific energy; and longer service life. In addition, they are more environmentally friendly since the danger of spilling toxic liquid into the environment is eliminated.
Solid polymer battery components generally include: positive electrodes (commonly referred to as cathodes); negative electrodes (commonly referred to as anodes); and an electrolyte separator which is capable of permitting ionic conductivity and which is sandwiched between the electrodes. Moreover, a current collector can also be associated with either one of the electrodes, especially the cathode.
In addition to acting as a mechanical support, the current collector also conducts the flow of electrons between the active material of the electrode and the battery terminals. Current collectors have a tendency to corrode or form an insulating film, which impairs the passage of electrons between the collector and the active material of the electrode, thereby increasing the internal resistance of the electrochemical cell and reducing power density and cycle life of such rechargeable batteries.
The current collector is also considered a passive component of the electrochemical cell because it normally does not generate energy. It simply provides a means for conducting the electrical current generated by the electrochemical cell. It is therefore advantageous to reduce the volume and weight of the current collector as much as possible.
Thus, there is a need for a relatively light and thin current collector which can better resist corrosion.